Abstract: Rupture of the anterior cruciate ligament (ACL) is one of most common ligament injuries of the knee and is often seen in the VA patient population. There are approximately 102,000 cases requiring surgery each year in the United States. The ACL is an important stabilizer of the knee and its integrity is required for many activities of daily living and sporting activities. In many veterans, the ACL is necessary for recreational sporting activities such as golf and softball and in some patients it is necessary for activities of daily living including walking. When injured, its absence leads to knee instability and often necessitates activity modifications in order to avoid symptomatic instability. In addition, there is evidence to suggest the knee joint will deteriorate if left untreated. Thus, the treatment of ACL injuries is aimed at restoring knee stability to prevent the associated complications of recurrent instability with subsequent damage to the menisci and articular cartilage. Current treatments for ACL ruptures require the use of grafts for reconstruction because the injured ACL has little healing capacity. Current graft options include the use of either autografts (tissue obtained from another uninjured part of the knee) or allografts (tissue obtained from a cadaver donor). Because of the inherent disadvantages with the use of these grafts, it would be advantageous to use a tissue- engineered ACL graft substitute. We are currently investigating ways that this could be accomplished in vitro for later implantation in vivo. The overall goal of this project is to develop a method for seeding a synthetic scaffold with autologous cells, cultivating the cell seeded construct under appropriate conditions in vitro and ultimately implanting it for knee ligament reconstruction. This approach could vastly change the treatment of knee ligament injuries and avoids the disadvantages and risks encountered with the current use of autograft and allograft tissue. This project will utilize a novel bioreactor in which polymer scaffolds created with electrospun fibers seeded with human adipose derived stem cells will be subjected to mechanical stimuli and growth factors in vitro as a preliminary step towards generating neoligament tissue which could later be implanted for ligament reconstruction. We hope to eventually engineer strong neoligaments for ACL reconstruction and the added morbidity associated with the use of autografts and allografts could be avoided. In addition, such a tissue engineering approach could potentially shorten the time necessary for rehabilitation following this type of surgery. PUBLIC HEALTH RELEVANCE: Project Narrative Potential Impact on Veterans Health Care: Because knee ligament injuries which require surgical reconstruction are common in the VA patient population, this proposal has the potential to directly influence the lives of veterans and thereby enhance the quality of services provided by the VA. Although current methods for ACL reconstruction are successful at restoring stability to the knee, there are many side effects and risks to surgical reconstruction due primarily to the use of a graft which is needed to rebuild the injured ligament. In fact, many veterans with this injury are denied surgery for this problem and thus must decrease their physical activity level because the risk of morbidity from the graft harvest is not justified and there are not enough allografts currently available for everyone with this problem. At our VA institution alone, over 150 ACL reconstructions have been performed over the last 6 years. Thus, this proposal can improve the management of ACL injuries in veterans. In addition, basic methods of ligament and tendon tissue engineering developed in this study could be directly applied to other common clinical problems in which tendon or ligament tissue is absent or deficient. These problems include shoulder (rotator cuff) and knee (quadriceps and patellar) tendon ruptures, which are also common in the VA patient population. Furthermore, the results of this research could be applied to engineering of other connective tissues including other tendons, fascia, and skin. Thus, this proposal could ultimately result in substantial improvements in the quality of life of veterans.